Central Massachusetts

We had our builders HVAC contractor in yesterday to check our system (gushing air in master bedroom). During his inspection he notice there was water between metal duct work and the insulation sleeve that cover the duct work.

The house was built last winter and wasn't fully weather tight when they installed the duct work.

He thought the water was there since day one, because he noticed the water that poured out was full of construction dust.

How is it possible that water can be present between the metal trunk and the insulation sleeve?

Could it be a condensation problem caused by the large contrast between the cold basement and the warm metal duct work?

Could it be that duct work insulation sleeve R value is to low; or could there be a system leak?

I also noticed there is no fiberglass insulation in the floor joist bays above the duct work runs.

The insulation was just stuffed in between the duct work runs, perpendicular to the floor joist bays.

Thanks